This gadget is also known as a digital Optical Coaxial Toslink Signal To Analog Audio Converter. The gadget converts digital audio into an analog signal. You have to agree that the sound that comes out of any TV is not up to the standards of amplifiers and av units. So in such situations we need to connect the TV to an amplifier or av unit for much better sound quality.
There are two types of ports that manufacturer’s use to provide us with an audio signal from their televisions. The first is an analogue method by using either RCA or headphone out jacks and the second method is by using a digital signal by either using a coaxial cable or an digital optical audio port.
The main advantage of using optical audio is that it has a much better audio quality. Better than using its analogue audio out counterpart plus it carries a much higher bandwidth of audio signal.
So why do you need such a device?
There are some amplifiers that do not have the optical audio in port connects to the TV. For this reason you need to buy the optical to rca audio converter.
In the image above you have the input ports of the converter. The most common method to connect a signal is to the converter is to use an optical cable directly connected to your TV.
Since it is a converter, it needs a source of power. This particular one used 5Volts. That is the voltage produced by the USB port of your TV so this particular manufacturer provides a USB cable that the user has to plug in either to the TV or another powered USB pot.
Connect the output port to the amplifier by using the normal AV cables. My suggestion before buying your own device is to check if the device comes with free optical cable.
The cost can vary from 4USD to 20USD